Select normals pointing in a certain direction
In most cases Make Normals Consistent (Ctrl+N) operator should help, see  Why are some faces in my mesh darker?. With all selected run it and it should make all normals pointing the right direction.  

However there are some cases when this won't work, i.e. it will consistently flip normals instead of making them pointing one direction. Probably there isn't yet solution exactly for every case like that, still you can use Non Contiguous option of Select Non-Manifold operator:


  Non Contiguous
      Selects edges that belong to exactly 2 faces with opposite normals.


link to manual

Execute it in Vertex or Edge Selection mode; it will select all edges which form problem faces, however depending on complexity of model selection won't form faces which you'd like to recalculate. You may want to run operator several times to feed all the faces to operator.